The priceless scroll was found in the archives of Bologna University, which was founded in 1088 and predates both Oxford and Cambridge.

The scroll, written in Hebrew, is 118ft long and 25 inches wide and consists of the first five books of the Jewish Bible, from Bereshit (the equivalent of Genesis) to Devarim (Deuteronomy).

It had been wrongly dated to the 17th century by a librarian who studied it in 1889, but it now transpires that it is more than 800 years old.

The discovery was made by Mauro Perani, the university’s professor of Hebrew.

He recently re-examined the scroll and noticed that the script was from a Babylonian tradition that suggested it was much older than previously thought.

The Torah, inscribed on soft lamb skin, also bore “letters and symbols” that were forbidden in later copies under rules laid down by Jewish scholars, Prof Perani said.

“At that point I sent photos of the scroll to some of the world’s leading experts. They all agreed that it dated to the 12th or 13th centuries. One scholar believed it could even date back to the 11th century.” The scroll was then subjected to carbon dating tests by the University of Salento in Italy and a laboratory at the University of Illinois in the United States.

The tests confirmed the scholars’ opinions, dating the text to between 1155 and 1225.

“That makes it the oldest complete Torah scroll in the world,” said Prof Perani.

Torah scrolls are extremely rare because most were eventually destroyed after being used in Jewish liturgies.

“When the manuscripts became worn out, it was considered that they lost their holiness. They could no longer be used for religious ceremonies and they were buried,” Prof Perani said.

Until now, the oldest Torah script in existence dated from the 14th century.

How the scroll ended up in Bologna remains a mystery, according to Biancastella Antonino, the head of the library.

It will be put on display next month at Bologna University. It will also be photographed and uploaded in digital format onto the library’s website.